Aly Song / Reuters
The trial is for the company's ACH-3102 inhibitor in combination with sofosbuvir, which is marketed and sold as Sovaldi by Gilead Sciences. In its most recent quarterly report, Gilead said sales of Sovaldi, which was approved by the FDA in December 2013, totaled $3.48 billion.
In its announcement Friday, Achillion said, "ACH-3102 continues to demonstrate good safety and tolerability through three Phase 2 studies. We believe these studies also confirm a differentiated efficacy profile for an NS5A inhibitor."
As a result of its findings, Achillion said 12 additional patients would begin treatment with six weeks of its ACH-3102 inhibitor with sofosbuvir.
Year-to-date, Achillion shares are up more than 190%.
Additionally on Friday, Gilead announced that an arbitrator ruled in favor of the company in a dispute with Roche related to a 2004 development agreement on sofosbuvir. Gilead shares were up as much as 2% on Friday.